Alloys are mixtures of two metals and not minerals. Gold and iridium are the only two metals found naturally as alloys. Gold is alloyed with a semi metallic element called Tellurium and Iridium forms a natural alloy with the metal Osmium called Osmiridium.
Actual minerals form from the chemical reactions of silicates and the oxides, sulfides, sulfates or carbonates of metals which are minerals themselves. Often the silicate will dissolve in alkaline water under tremendous heat and pressure. It will recrystallize together with metal ions forming gems like beryl, emerald or garnets. Diamonds are just a crystalline form of carbon. It forms diamond crystals out of solutions of molten iron like sugar can form crystals in a sugar solution. Carbon is soluble in liquid iron.